How and what to analyze firewall logs?

How and what to analyze in a firewall log?

Analyzing the logs collected by the firewall helps to understand the network traffic better. It is always recommended to refrain from checking just the dropped packets. Every activity happening in the firewall is an indication of what's entering and happening in your network. Therefore, it's essential for you to enable logging in firewalls and analyze them on a regular basis.

Below are some of the critical firewall events that you must constantly monitor.

• Traffic dropped/allowed
• Firewall started/stopped/restarted
• Authentication events
• Administrative permissions
• Modification of firewall rules

Methods of analyzing firewall logs.

Firewall logs can be analyzed either manually or with the aid of a log management solution. While analyzing manually can be a tiring process, a log management solution can automate the log collection and analysis process, provides you with insightful reports for critical events, notifies in real-time results upon the occurrence of anomalies that can help taking necessary actions.

Tips for analyzing your firewall logs:

• Aggregate your firewall logs to a centralized server. This helps in efficient monitoring of the logs as you can sift through firewall log data from different time period and even correlate them with other log data in the network. Also, centrally aggregating log data is one of the important requirements of the most popular regulatory mandates.
• If you're manually analyzing the firewall logs, you can use easily available tool such as Notepad++ and MS Excel to extract fields and analyze them for effective troubleshooting.
• With Notepad++ or Notepad, you can make use of the "Find" option to look for specific IP or log fields.
• MS Excel serves better than Notepad in terms of analysis. Options such as Sort, and Filter are highly useful when you want to group a specific events and want to find the number of times an event has occurred.
• Though both these tools are simple to use, it is very difficult when you want to perform in-depth analysis, and correlate the log data to track down a security threat.
• Alternatively, you can opt for any log management solution (such as ManageEngine EventLog Analyzer) that does everything starting from collection, analysis, to correlation and storage for you. Make sure that the solution comes bundled with predefined reports and alert profiles that captures critical events stated above.

Check out EventLog Analyzer, a comprehensive log management solution which helps monitor the firewall activities and provide reports on user logons, policy changes, firewall status, etc.